GROWTH-FACTORS IN CHROMAFFIN CELLS

Chromaffin cells, the neuroendocrine cells of the adrenal medulla and paraganglia, occupy paradigmatic roles in molecular, cellular and deve lopmental neurobiology. The fact that they are very effective 'minipum ps', secreting numerous bioactive substances including amines, neurope ptides and proteins, has made them interesting and useful for the trea tment of chronic pain and Parkinsonism. An essential advantage of chro maffin cells is that they can be isolated and purified in extremely hi gh numbers, which can never be achieved for peripheral or central nerv ous system neurons. Growth factors (cytokines) and peptides with growt h factor-like efficacies constitute an important component of bioactiv e materials released from chromaffin cells. Not only their presence, b ut also neural and humoral mechanisms regulating their expression and release, are now being revealed. Prominent examples include fibroblast growth factors (FGFs), transforming growth factor-beta s (TGF-beta s) and interleukins. Functions that can be assigned to these factors in the adrenal medulla are gradually emerging. For example, FGFs and TGF- beta s can regulate chromaffin cell proliferation and differentiation and participate in the neurotrophic maintenance of neurons innervating chromaffin cells. Ln contrast, the functions of the predominant secre tory proteins of chromaffin cells, the chromogranins, are still largel y unknown, but might include cytokine-like roles. Thus, chromaffin cel ls continue to teach neurobiologists about the fundamental capacity of neurons to secrete bioactive molecules with a wide range of functions as well as modes of their secretion underscoring the close relationsh ip of endocrine and neuronal systems. Copyright (C) 1996 Elsevier Scie nce Ltd